(1) Field of the Invention
The present invention relates to a global subscriber group service system for providing various services for a global subscriber group.
(2) Description of the Related Art
In recent years, services for a global subscriber group have become available in public telephone networks for providing predetermined types of special services for specific subscribers in the global subscriber group. The predetermined types of special services are, for example, a service for using a virtual private network or a service for using an extension number to connect the subscribers in the global subscriber group. Such services mentioned above are hereinafter referred to as global subscriber group services.
In the prior art, the subscribers who can enjoy the global subscriber services are limited to subscribers in the global subscriber group, such as subscribers accommodated to a private branch exchange (PBX) or a centralized exchanging switch (CES). In the following discussion, the subscribers that are accommodated to PBX or CES are occasionally referred to as "group subscribers" or PBX/CES subscribers.
In general, the conventional service providing system for a global subscriber group includes a plurality of local switching nodes each for accommodating individual subscribers and PBX/CES subscribers and a service control node that carries out a centralized control of the local switching nodes. The local switching nodes are mutually connected through a public network, virtual private network, or private lines, as later described in more detail with reference to the drawings.
Conventionally, only specific PBX/CES subscribers can use the global subscriber group services, by previously registering entry into the global subscriber group service network through a maintenance person.
In practice, to enjoy the service for utilization of the virtual private network, conventionally, the type of utilization including various items of, for example, the corresponding relationship between the calling subscriber and the receiving subscriber, the numbers of the subscribers, the communication route, time schedule, etc., has to be registered by a maintenance person.
Further, to enjoy the services of a global extension number connection service, conventionally, an actual terminating terminal (physical number) corresponding to a global extension close number (logical number) has to be registered in the network through a maintenance person to provide the service for specific group subscribers. In addition, modification of a registered terminal and the type of services is not possible even for specific subscribers belonging to the global subscriber group.
As mentioned above, in the conventional global subscriber group service, the subscriber group services have been realized only for specific PBX/CES subscribers. Furthermore, a global subscriber group service modification function, which allows the subscriber to flexibly modify registered types for various services to be used, is not available. Therefore, in the prior art, only less flexible and less responsive global subscriber group services can be provided.
On the other hand, in the extension close number connection service for global PBX/CES subscribers, there is a problem in the prior art that the subscriber who uses the global extension number connection service, is limited to the PBX/CES subscribers previously registered in the network. Also, a problem is encountered in the prior art in that a flexible control function including a capability or permitting individual subscribers to use this type of service, is not available.
Furthermore, in the conventional service providing part of the public network as the virtual private network, the subscribers who can use the virtual private network are limited only to the PBX/CES subscribers previously registered in the network. Therefore, in the prior art, a flexible control function permitting any customer to modify the type of registered services of the virtual private network is not available.
In recent years, it has been desired to provide such type of global subscriber group services including use of a virtual private network or service for assigning individual subscribers as terminals in a virtual extension system (including a service for connection to an internal closed number), with respect to a high level global subscriber group including not only PBX or CES subscribers but also individual subscribers.